1. Field of the Invention
The present invention relates to a method for producing a spark plug.
2. Description of the Related Art
Such a spark plug is known, for example, from published European patent document EP 0 269 267 B1. The spark plug has a housing on which a ground electrode is fixed. In the housing, there is an insulator having a longitudinal bore in which a center electrode is situated. By the application of a high voltage, a spark gap extends between the center electrode and the ground electrode. Based on the increasing requirement for engine performance in combination with more fuel-efficient engines, there is a demand for improvement in ignitability of spark plugs. It is known that spark plugs have been proposed, for this purpose, in which a first noble metal pin is connected to the area of an end face of a ground electrode and a second noble metal pin is connected to the end face of a center electrode. The two noble metal pins are opposite to each other, that is, the axes of symmetry of the two noble metal pins are situated on one line.
The welding seam is located on the circumference of the boundary layer between the noble metal pin and the end face of the ground electrode, and, in the most favorable case, it extends over the entire circumference (360°) of the interface.
The first disadvantage of the usual production method is that a costly welding process is required on the mounted spark plug in order to ensure the accurate covering of both the noble metal pins. A further disadvantage results from the sequence of the known method steps. Since the ground electrode is already connected to the housing of the spark plug before the noble metal pin is connected to the end face of the ground electrode, an encircling welded joint between the ground electrode and the noble metal pin cannot be reliably achieved, since the full circumference is not available for the welding process.